JSP 2.0 SEO friendly links encoding

Question

Currently I have something like this in my JSP

<c:url value="/teams/${contact.id}/${contact.name}" />

The important part of my URL is the ID, I just put the name on it for SEO purposes (just like stackoverflow.com does).

I was just wondering if there is a quick and clean way to encode the name (change spaces per +, latin chars removal, etc). I'd like it to be like this:

<c:url value="/teams/${contact.id}/${supercool(contact.name)}" />

Is there a function like that out there or should I make my own?

Swann

Answer 1

Nothing like that is available in JSTL functions. You'll need to create your own. I'd by the way rather replace spaces by -.

To the point, you want to perform the following steps:

1. Lowercase the string.

   string = string.toLowerCase();
   

2. Normalize all characters and get rid of all diacritical marks.

   string = Normalizer.normalize(string, Form.NFD).replaceAll("\\p{InCombiningDiacriticalMarks}+", "");
   

3. Replace all remaining non-alphanumeric characters by - and collapse when necessary.

   string = string.replaceAll("[^\\p{Alnum}]+", "-");
   

You can wrap this in an EL function:

package com.example;

import java.text.Normalizer;
import java.text.Normalizer.Form;

public final class Functions {
     private Functions() {}

     public static String prettyURL(String string) {
         return Normalizer.normalize(string.toLowerCase(), Form.NFD)
             .replaceAll("\\p{InCombiningDiacriticalMarks}+", "")
             .replaceAll("[^\\p{Alnum}]+", "-");
     }
}

Which you register in a /WEB-INF/functions.tld like follows:

<?xml version="1.0" encoding="UTF-8" ?>
<taglib 
    xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"
    version="2.1">

    <display-name>Custom Functions</display-name>    
    <tlib-version>1.0</tlib-version>
    <uri>http://example.com/functions</uri>

    <function>
        <name>prettyURL</name>
        <function-class>com.example.Functions</function-class>
        <function-signature>java.lang.String prettyURL(java.lang.String)</function-signature>
    </function>
</taglib>

Which you can use in JSP as follows:

<%@taglib uri="http://example.com/functions" prefix="f" %>
...
<a href="teams/${contact.id}/${f:prettyURL(contact.name)}">Permalink</a>

Philippopolis

By the way, is there any doc regarding using - instead of + for spaces? – Swann

No, someone else did :) The downvote was a while after my update. The reason that the - is preferred is because the + is actually the "URL-safe" character for a space, not intended for SEO purposes. Look how Stackoverflow and another major sites do it. – Philippopolis

Answer 2

Look for server.urlencode, all the major server side languages today have them.

Blinker

This only applies percent encoding. That's not really exactly what he's asking for. It would otherwise indeed have been a very straightforward answer :) It's by the way called java.net.URLEncoder. Not server.urlencode or something C-ish like that. – Philippopolis